Eliminating squirrels and other uninvited guests such as pigeons from feasting at bird feeders intended for small birds has long been a problem.
U.S. Pat. No. 3,977,363, has sought to squirrel proof a hanging bird feeder by providing a dual pitched roof. As the squirrel moves down the roof, the bird feeder, which hangs from a chain, tips and dumps the squirrel. This device depends on the pivoting action of a hanging bird feeder and will not perform well for large feeders where the center of gravity will not be greatly effected by the motion of the squirrel on the roof.
The limitation of the '363 patent to hanging bird feeders has, in part, been overcome for pole mounted feeders by using baffles mounted below the feeder such as is taught in U.S. Pat. Nos. 4,389,975 and 4,259,927. The use of baffles requires additional parts and will neither provide protection from uninvited flying guests nor, for that matter, from jumping squirrels. To overcome the problem of jumping squirrels, the '975 patent proposes a feeder which is rotatably mounted on a post to provide a "merry-go-round" effect to discourage jumping squirrels.
Thus, there is a need for a simpler bird feeder which is effective in warding off uninvited guests.